Crankshaft and method of making same



June 7, 1949. L. MUELLER CRANKSHAF'I' AND METHOD OF MAKING SAME Filed Aug. 10'. 1944 IN VEN TOR.

R a E N L R l- E m U T A L R E W H w Patented June 7, 1949 TENT OFFICE F CRANKSHAFT AND METHOD OF MAKING SAME Homer L. Mueller, Cleveland, Ohio, assignor to The Cleveland Welding Company, Cleveland, Ohio, a corporation of Ohio Application August 10, 1944, Serial No. 548,833

1 Claim.

This invention relates as indicated to crankshafts and method of making the same and more particularly to a crankshaft which is formed of a tubular body whereby the ultimate structure may be produced much more economically than the forgings which are used at the present time.

It is a further object of my invention to provide a structure which, because of the tubular nature of the blank from which it is made, has much less weight than the heavier solid structures of the prior art.

It is a further and more particular object of the invention to provide a structure which because of its tubular nature will facilitate the circulation therethrough of lubricants, cooling media, and the like.

It is still another object of my invention to provide a method of making such a crankshaft which is not only economical but which will also result in a'finished structure having the proper characteristics.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claim, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing- Fig. 1 is a broken side elevation of a blank from which my improved crankshaft may be made, showing mounted thereon induction heating coil as per one of the steps in the improved process also forming a part of my invention;

Fig. 2 is a view showing an intermediate stage in the operation of forming the crankshaft and wherein the first series of reduced areas are formed between certain of the bearing areas;

Fig. 3 is a view showing a more advanced stage in the manufacture of the crankshaft; and

Fig. 4 is a view of a portion of the crankshaft blank shown in the previous figures and illustrating the manner in which one of the radially displaced crank arms on the shaft may be formed.

Referring now more specifically to the drawing and more especially to Fig. l, as the first step in the new process of forming my improved crankshaft, I provide a cylindrical blank generally indicated at l which is preferably a seamless tube of alloy steel of such composition as to provide not only the necessary workability for the ensuing steps in the process, but also the necessary strength and rigidity in the final product. There are many alloys available for this purpose and since the composition of the tube forms no part of the present invention, it is believed unnecessary to more specifically define the same.

As the first step in my improved process, .I locally heat an area 2 of the blank land this can be accomplished by any suitable means such as for example by means of an induction heating coil generally indicated at 3 which in effect comprises the primary of a transformer with the portion of the blank I therein comprising a one-turn secondary of such transformer.

The area 2 is thus heated sufficiently so as to render the same readily workable as for example between a pair of rolls 4 and 5 which are peripherally contoured as illustrated in Fig. 2 and which are capable of reducing the diameter of the blank I in the heated area. The width or axial extent of the rolls 4 and 5 will depend upon the dimension of the finished crankshaft under con struction, it being observed that the areas 6 and l which lie immediately outside of the area engaged by the rolls 4 and 5 will, in the final form. constitute the main bearing areas of the crankshaft.

A series of reduced areas 8 and 9 and III are thus formed in axially spaced relation on the blank I, leaving therebetween the said main bearing areas.

The local areas 8, 9, and I0, after being thus formed, as illustrated in Fig. 2, are again heated to a workable temperature by some suitable means such as induction heating and are thereafter again engaged by a second pair of rolls H and F2 which have the function of further reducing the major portion of the diameter of such areas 8, 9, and ill by leaving intermediately thereof a series of axially spaced slightly enlarged areas such as l3, which in the final fabricated form of the crankshaft will constitute the connecting rod bearing areas.

After the blank is formed in the manner illustrated in Fig. 3, the entire axial extent of the blank shown embraced by the rolls II and I2 in Fig. 3 is again heated to a suitable working temperature, whereupon a pair of dies l4 and I5 are brought into engagement with such heated area to radially displace from the main axis of the crankshaft, i. e. the axis of the main bearing areas, the connecting rod bearing area l3. In this last forming operation, it will be observed, of course, that the main bearing areas 6 and l are brought axially closer together, and in the design of the rollers employed in the previous steps of the process due allowance must be made for such axial movement.

By the die forming operations just described, I am able to produce a crankshaft blank which is substantially the size and shape of the desired end product. *After the crankshaft has been formed by rolling a'nd iorging or 'die working in the manner just described, the several axially 4 fiow throughout the entire length of the shaft, thus contributing to the necessary strength and rigidity of the shaft.

Other modes of applying the principle of the invention may be employed, change being made spaced bearing areas thereon are then ground touo'ltinctly claim as my invention:

approximately the desired finished diameter and the bearing surfaces then completed by means of a lapping operation as in a conventional crankshaft lapping machine, of which therezarea 'number available on the market.

It will be observed that by the exercise of the proper care as by way of a-careful control-over the extent to which the blank isheate'd and' the degree and manner in which it is deformedinlthe various forming steps, it-is possible to end up with "a structure having 1? a -.con-tinuous passage therethrough. Suchc'ontinuouspassage makes possible the circulation through the crankshaftof a .suitable lubricant and/or 'cooling medium, as vfor example lubricating oil under pressure. When lubricating oil under pressure is circulated through the cranksh'aft, =th'en --radial openings through the wall of the :finishedstructure in the bearing areas Will -provide means -whereby'such :b'earing areas-arealways supplied with adequate lubricating oils; 0n theother hand; in certain types of engines, "it is'possible'to-employ a coollng medium such :as-=a'-flow of air through the crankshaft for the purposeof cooling-the: same during use.

- The improved crankshaft of my invention will lie found-to have not-only 'the'necessary strength andrigidity, but will. also be=capable of fabricaltio'n much more economically thanthe solid structures now being employed because it is much easier to thus shape tubular member than a solid structure.

Forming the crankshaft of I a. seamless-tube in the manner 1 above explained in carrying I out my improved-method-will result: in a str-ucturein Number which there-is a substantiallycontinuous grain The method of forming a crankshaft such as :tl'i'oseusedin'internal combustion engines which comprises providing a cylindrical blank of di- -'zameter-x-corresponding substantially with the dim ameter of theimain'bearings of the final form of cranksha'ft, 'heating a portion of the length of the b1ank.to a.workable. state, rolling and forming in such heated portion an elongated reduced section of uniform reduced diameter corresponding substantially with the diameter of the connecting rod bearingsiof'uthe final form zofcrankshait, further rolling :said elongated. reduced iportionsat. spaced points to: Iea-ve-intact -an intermediate. connecting rod'bearing'of-a:sizeaszsecured'by saidffirstrolling and to form sections-of further reducedsize. corretheyare tooccupy:v in the final iormof crankshaft.

HOMER L. MUELLER.

" "REFERENCES "CITED flheiollowing references-are of ..record ..in..the

file of this patent:

UNITED STATES' PA-TENTS Number Name .I Date 240 1,763,338 -Auerbach .June.10,.-1930 2,142,805 Ryder -.Jan..3,.l939 2,175,156 Mummert 5901;. .3, $1939 FOREIGNZTEATENIS Country Date 13,004 Great Britain "OCt.' 29,1885 

